The Colorados were the final group of Standard-type battleships, designed to have similar speed and handling to simplify maneuvers with the line of battle. (The South Dakota class which was to follow would in several ways have been a departure from this practice.) Apart from an upgrade in striking power to eight 16-inch guns, the ships were essentially repeats of the earlier Tennessee class. The Colorados were also the last American capital ships built with four turrets and twin-mounted guns. The change to larger guns was prompted by the Japanese Nagato-class battleships, which also mounted eight 16-inch guns.

All three ships had extensive careers during World War II. Maryland and West Virginia were both present during the attack on Pearl Harbor on 7 December 1941. Maryland escaped relatively unscathed; West Virginia was sunk in the shallow waters of the harbor but subsequently raised and repaired. All three ships served as artillery support ships during amphibious operations. Maryland and West Virginia were present at the last surface action between battleships, the Battle of Surigao Strait during the Battle of Leyte Gulf in October 1944. The three ships, put into the reserve fleet after the end of the war, were scrapped by the late 1950s.

The construction of battleships armed with 16-inch guns was envisioned by the United States Navy General Board and Bureau of Construction and Repair (C&R) as early as 1913, as the upgrade in gun caliber promised twice the kinetic energy of the 12-inch gun then in service and half again as much as the 14-inch gun then being introduced. This weapon dominated the design of battleships between 1913 and 1916, just as the 12-inch gun had dictated designs from 1908 to 1910. However, while the General Board approved the 16-inch gun as early as 1911, the secretary of the navy felt that a move to a new gun caliber might make capital ships still on the drawing board obsolete. For this reason, he restricted the Bureau of Ordnance to proceed no further than blueprints for the new gun as a hedge against foreign developments. He finally approved construction of this gun in October 1912 and the weapon was test fired successfully in August 1914. This success, along with the unofficial news in several naval publications of 15- and 16-inch weapons being adopted by Britain, Italy, Germany and Japan, the Board considered abandoning construction of the Pennsylvania class in favor of an up-gunned design. Such a move meant an increase of 8,000 tons per ship, twice as much as the jump from the Nevadas to the Pennsylvanias. Debate continued for the next three years. Each year, President Woodrow Wilson's secretary of the navy, Josephus Daniels, balked at the potential increase in cost and ordered instead that the design features of Standard Class be upheld. Daniels finally compromised with the 1917 design battleships by allowing their armament to be upgraded. This, however, was to be the only substantial change to be allowed.[3]

Hull of Maryland under construction c. 1917

The design of the Colorado class, therefore, was taken from the preceding Tennessee class; other than the notable improvement of eight 16 in (410 mm)/45 caliber in four dual turrets taking the place of the Tennessee-class's twelve 14 in (360 mm)/50 caliber guns in four triple gun turrets, there was not a major difference between the two designs. Likewise, the Tennessees were the results of modifications to the New Mexico class, which had been the most modern US capital ships to see service in World War I and had attracted the attention of British constructors both serving with and outside C&R. This similarity would carry over into the Lexington and South Dakota classes as the United States Navy increasingly standardized its capital ship designs. This was partly the result of wartime experience, when over 250 destroyers and more than 450 submarine chasers had to be built quickly for service in the North Atlantic. The U.S. Navy had done this by a process almost akin to the assembly line, sticking to one basic design per class with a maximum amount of standardization and rationalization. Since the Naval Act of 1916 meant the imminent construction of 16 battleships and six battlecruisers, it was necessary to streamline production to save time and labor.[1][4][5][6]

Nevertheless, while US battleships were standardized as much as possible, design improvements were incorporated whenever possible. Most of the changes in the Tennessees were incorporated prior to any of their keels being laid. However, plans for the underwater protection—the ships' main defense against torpedoes and shells that fell short of the ship but traveled through the water to hit underneath the waterline—could not be worked out in time. The problem was that tests in caissons—experiments that would eventually prove that a series of compartments divided between being filled with liquid and being left empty would be a very effective defense against torpedoes—were not yet complete. In order to commence construction of the ships as soon as possible, bids sent out to shipbuilding corporations noted that if they were selected to build the ships, an alteration to the design of the ships three months after their keels were laid must be allowed.[7][8]

The Colorados were extremely similar overall to the Tennessees, with a 624-foot (190 m) overall length and a beam at the waterline of 97 feet (30 m). They displaced 32,600 long tons (33,100 t) at normal load and 33,590 long tons (34,130 t) at deep load and had a draft of 30.5 feet (9.3 m). Like the Tennessees, they were designed with a clipper bow to make the ships dryer in rough weather. One improvement over previous classes was the location of the secondary battery in the superstructure rather than the upper hull, where it had proved to be excessively wet.[9][7]

Turbo-electric transmission, which had been used in the prior class, was retained here. Advantages included the ability for the turbines to run at optimum speed without regard to propeller speed, which led to greater fuel economy and range, and an easier sub-division of machinery, which increased the ships' ability to withstand torpedo hits. Each of the four propeller shafts was powered by a 5,424 kilowattelectric motor, fed by two two-phase turbo generators (General Electric for Maryland, Westinghouse for Colorado and West Virginia) rated at 5,000 volts). Eight oil-fired Babcock & Wilcoxwater-tube boilers, each in its individual compartment, provided steam for the generators. Altogether, the ships' power plant was rated at 28,900 electrical horsepower (EHP) to provide a flank speed of 21 knots (39 km/h; 24 mph). With a maximum bunker capacity of 4570 tons, the Colorados' range without refueling at sea was 10,000 nautical miles (19,000 km; 12,000 mi).[10]

The Colorado class was armed with eight 16-inch (406 mm)/45 caliber Mark 1 guns, which fired a 2,100-pound (950 kg) armor-piercing (AP) shell at a muzzle velocity of 2,600 feet per second (790 m/s) and a rate of about 1.5 rounds per minute to a range of 34,300 yards (31,400 m) at a maximum turret elevation of 30 degrees. Development of this weapon had begun in August 1913, using a bored-out and relined 13-inch (330 mm) Mark 2 gun, with the promise of twice the muzzle energy of the 12-inch (305 mm)/50 caliber Mark 7 guns and 50 percent more than the 14-inch (356 mm)/45 caliber weapon used on the Nevada-class battleships. After an initial proof firing in July 1914 and minor changes, the 16-inch Mark 1 was re-proved in May 1916 and production approved in January 1917. When the Colorados were modernized in the 1930s, these guns were rebuilt per standard navy practice and redesignated 16-inch/45 (40.6 cm) Mark 5 and Mark 8.[5]

Fourteen 5-inch (127 mm)/51 caliber Mark 15 guns were installed to defend against enemy destroyers. This was reduced to 12 in 1922. The Mark 15 fired a 50-pound (23 kg) shell at a velocity of 3,150 feet per second (960 m/s) to a maximum range of 14,400 yards (13,200 m) at 45 degrees at a rate of seven rounds per minute and was extremely accurate, with a danger space longer than the range to the target for distances less than 3,000 yards (2,700 m). As in the New Mexico and Tennessee classes, these were mounted in unarmored casemates on the main deck, one deck higher than in previous classes, to allow them to be manned in heavy weather if necessary.[11][12]

In 1942, the Mark 15 guns were replaced on West Virginia with sixteen 5-inch (127 mm)/38 caliber Mark 12 dual-purpose guns in twin turrets. On Maryland and Colorado ten Mark 15s were retained and augmented with eight 5 in/38 cal Mark 12s in single mountings with protective shields; the twin turrets planned and later installed were at that time in short supply. The Mark 12 fired a 55.18-pound (25.03 kg) shell to a maximum range of 17,392 yards (15,903 m) and a maximum elevation of 37,200 feet (11,300 m) at an elevation of 45 degrees.[13] They had a high rate of fire due to their being hand-loaded but power-rammed and their capability for easy loading at any angle of elevation. The introduction of proximity-fused anti-aircraft shells in 1943 made the 5 in/38 even more potent in this capacity.[14]

USS West Virginia in her final configuration, June 1944. Note 5 in/38 twin turrets and number of AA guns

Four 3-inch (76 mm)/23 caliber guns were mounted initially for anti-aircraft (AA) defense. This was increased to eight guns in 1922. These guns fired a 3-inch (76 mm) shell at a muzzle velocity of 1,650 feet per second (500 m/s) to a maximum range of 8,800 yards (8,000 m) and ceiling of 18,000 feet (5,500 m) at an elevation of 45.3 degrees and a rate of between eight and nine rounds per minute.[15] These weapons were replaced in 1928-9 with the same number of 5-inch (130 mm)/25 caliber guns, the first Navy gun designed specifically for AA use. They fired a 54-pound (24 kg) shell at a muzzle velocity of 2,155 feet per second (657 m/s) at a rate of between 15 and 20 rounds per minute to a maximum range of 14,500 yards (13,300 m) at an elevation of 45 degrees and a ceiling of 27,400 feet (8,400 m) at a maximum elevation of 85 degrees.[16] These guns were supplemented with eleven 28 mm machine guns in 1937-8.[17]

In 1942, the air defense system on these ships was overhauled completely. In addition to her 5 in/38s, they carried sixteen Bofors 40 mm guns in quad mounts and up to thirty-two Oerlikon 20 mm cannons in single mounts. The quad 40 mm Bofors fired a 1.985-pound (0.900 kg) at a rate of 120 rounds per minute per barrel nominal, 140 to 160 rounds per minute when horizontal (gravity assist), to a maximum range of 11,133 yards (10,180 m) at 45 degrees and a ceiling of 22,299 feet (6,797 m). The 20 mm Oerlikons fired a 0.271-pound (0.123 kg) shell at an average muzzle velocity of 2,725 feet per second (831 m/s) and a practical rate of between 250 and 320 rounds per minute to a maximum range of 4,800 yards (4,400 m) at 45 degrees and a ceiling of 10,000 feet (3,000 m).[18][19][20]

A second overhaul of AA defense was made between 1944 and 1945, as the Navy had found 20 mm shells too light to stop Japanese kamikaze planes; this plus the higher approach speeds of these planes made these manually controlled guns obsolete. In their place, more quad 40 mm Bofors mounts were fitted. Maryland eventually carried forty quad 40 mm and eighteen 20 mm guns. Colorado's quad 40s were increased to forty but she kept all her 20 mm guns. West Virginia carried forty quad 40 mm and fifty 20 mm.[18][19][20] guns.

The "all or nothing" armor scheme introduced in the Nevada-class battleships was continued here, as throughout the Standard-type warships, with armor suite virtually identical to the preceding Tennessee class. The exception was an increase in belt armor near vital machinery to 16 inches (410 mm) to correspond with the increased main gun caliber. Otherwise, the minimum thickness along the belt remained 14 inches (360 mm). Upper deck armor was 3.6 inches (91 mm) initially and was later increased to 4.1 inches (100 mm). Lower deck armor ranged between 2.25 and 1.5 inches (57 and 38 mm) and was also presumably strengthened during conversion.[17]

As with the Tennessees, the Colorados were modernized in the 1930s to improve their staying power. A new underwater protection scheme featured five compartments separated by armored bulkheads.75 inches (19 mm) thick on either side of the ship: an outer empty one, three filled, and an empty inner one. In addition, the eight boilers were moved from their location in previous designs and placed in separate spaces to port and starboard of the turboelectric power plant. This arrangement formed another line of defense, which would allow the ship to sail if one or even an entire side of boilers was incapacitated. A consequence was the chief aesthetic change between the New Mexicos and Tennessees: the single large funnel of the former was replaced by two smaller funnels in the latter.[8][21]

Other improvements imported from the Tennessee class included an attempt to move the forward torpedo room away from the 16-inch gun magazines, as the room was viewed as vulnerable. Also, the design called for the use of external, rather than internal, belt armor so that a "break in the continuity of the side structure" would not exist, which would minimize drag in the water and any corresponding waste of power.[8][22]

Plans for modernization of the Tennessee and Colorado classes were made in October 1931, in part to take advantage of loopholes in the Washington Naval Treaty. While reconstruction under this treaty was allowed only to increase protection from air and underwater attack, it could include improvements in fire control and increased elevation for main armament as these items were not listed in the treaty. Also, any changes made inside the hull could be justified as meant to increase protection, even if the outcome meant increased speed or longer operational range, since the term "blister" had been specified to limit changes only outside the hull, such as main armor belt thickness and main gun caliber. Modifications to the secondary battery were also outside the purview of the Washington Treaty.[25]

Included in initial plans was some protection against chemical shells which contained poisonous gas, although the General Board stated in the late 1920s that decontaminating a battleship hit with these shells would not be possible—the ship would have to be scuttled. Also, the deck armor was to be bolstered with 80 lb (36 kg)-special treatment steel (STS)—which would add 1,319 long tons (1,340 t; 1,477 short tons) to the displacement of the ships—the armor on the tops of the main turrets was to be made thicker, fire controls were to be improved with the latest technology, and new shells for the main guns were to be designed. Two, later four, 1.1"/75 caliber machine cannons were to be added, and all of the machinery in place would be removed in favor of newer equipment so that the ships would not lose any speed with the great increase in weight. Blisters were also to be installed to improve buoyancy but not to increase the ships' beams any greater than 106 feet (32 m) so they could still use the Panama Canal when transferring from the Atlantic to the Pacific and vice verse. These improvements were estimated to cost about $15,000,000 per ship ($71,723,000 total). However, with the country in the throes of the Great Depression, not much money was available for the Navy. Savings of $26,625,000 could be realized by reconditioning the propulsion machinery rather than replacing it, which would lower the ships' speed. Adding protection against chemical shells could be dropped, along with development of the new shells. Nevertheless, the cost-saving elements of the later proposal were later dropped. The Navy asked the Secretary of the Navy to request money in the fiscal year 1933 to modernize the two classes from Congress, but the depression worsened. Although proposals for modifications were still made, plans were put on hold and never carried out.[26]

West Virginia in October 1935 off Hawaii

In the beginning of 1934, the Bureau of Construction and Repair proposed that the "Big Five"—the two Tennessees and three Colorados—be fitted with anti-torpedo bulges so that the ships could benefit from increased buoyancy; because of, among other factors, the normal procedure of leaving port with the maximum amount of fuel possible on board, the five ships were quite overweight and rode low in the water. For example, in June 1935, Tennessee had a normal operating displacement of 38,200 long tons (38,800 t; 42,800 short tons)—more than 2,000 long tons (2,000 t; 2,200 short tons) above the maximum emergency load her original design called for. This made her draft higher—meaning that the ship's waterline was down 5 ft 4 in (1,630 mm). Construction and Repair called for a bulge on the Colorados that would displace about 2,000 long tons (2,000 t; 2,200 short tons) and raise the ships' draft by 20 in (510 mm). Installing these would be a year's worth of work, with each ship spending six months of that in a dry dock—the first month docked so that the hull shape could be determined, the next six sailing while the bulge was built, and the last five back in the dock so it could be added to the ship.[27]

Three years later (1937), the various Navy bureaus held a joint meeting to discuss a possible partial modernization of the Tennessee's and Colorado's. They were much different than the changes proposed in 1933; there were no provisions for extra deck armor, but many additions and replacements. To gain space for newer fire control systems, the ships were to be reboilered. The main and secondary battery fire controls were to be replaced, including new rangefinders and plotting room instruments for the main, while new Mark 33anti-aircraft fire control directors were planned. The mainmast and M2 Browning machine guns would be removed, and studies of the feasibility of a torpedo bulge, the addition of which Construction and Repair believed to be paramount, which would increase the beam to 108 ft (33 m) and displacement to 39,600 long tons (40,200 t; 44,400 short tons). Varying plans for these were complete by October 1938. None was a full reconstruction; costs ranged from $8,094,000 to $38,369,000 per ship. However, as the money for the improvements would lessen the amount available for new battleship construction, and these would be better than even reconstructed old battleship, the Secretary of the Navy rejected these plans in November. Congress did appropriate $6,600,000 in 1939 for some of these improvements, including the bulges.[27]

With the beginning of World War II in Europe, the Navy began to apply lessons learned by the British to U.S. ships. The KingBoard of 1940–1941 proposed sweeping changes to the secondary armament of the battleships to increase their defense against air attacks. These included the removal of all 5 in (130 mm)/25 caliber guns and 5 in/51 in favor of the dual-purpose5 in/38, the addition of six quadruple 1.1 in (28 mm) machine cannons, and the cutting away of superstructure to clear arcs of fire for the new anti-aircraft weapons. An ultimate secondary battery of sixteen 5 in/38 in dual mounts, sixteen Bofors 40 mm in quadruple mounts and eight single Oerlikon 20 mm was called for by the board in 1941, although they were not certain the ships could handle the added weight and it would take a large amount of time in dry dock for these modifications to take place. With these concerns, an interim measure of four 1.1 in guns was proposed by the board; however, the gun was not being produced in any great number very quickly, so a second interim solution was implemented. 3 in (76 mm)/50 caliber guns were added to all of the U.S.' battleships except for Arizona and Nevada by June 1941; these were replaced on the three battleships in the Atlantic by the 1.1 in by November—they received them first because they were closer to a war zone.[28]

As these modifications were carried out upon the various battleships, much additional weight was added onto the already overweight ships, forcing torpedo bulges to be added so that a decent freeboard could be maintained. These would cost $750,000 and around three or four months in a dry dock. The King Board suggested that the deck armor be bolstered and 5 in/38 dual-purpose guns be added, but the Chief of Naval Operations decreed that any major changes such as these had to wait due to the wars raging around the world at the time. The addition of bulges, however, was approved for the "Big Five", with each ship spending three months in dry dock at the Puget Sound Naval Yard. Maryland would be first (17 February 1941 to 20 May), followed by West Virginia (10 May to 8 August), Colorado (28 July to 28 October), Tennessee (19 January 1942 to 21 April) and California (16 March to 16 June).[b] However, the estimates for how long the addition of bulges would take were too low; Puget Sound believed that they could complete work on Maryland in 123 calendar days (about four months)—if the work would be given a priority equal to that of Saratoga's refit and higher than new construction.[27]

Only two of the ships had bulges added to them through this program, Maryland (completed 1 August 1941) and Colorado (26 February 1942); the attack on Pearl Harbor interrupted the refits intended for West Virginia and the two Tennessees. The surprise strike did not touch Colorado, which was at Puget Sound, and did not hurt Maryland very badly; however, West Virginia was severely damaged and needed a major refit at minimum.[29]

Maryland on 9 February 1942, little changed from her pre-war configuration

Little to no major modifications were made to the two active Colorados in the opening months of the U.S.'s entry into the war; all of the battleships in the Pacific Fleet had a constant order to be ready to sail within 48 hours in case of a Japanese attempt to invade Hawaii or the West Coast and could not be spared for any major yard work. Colorado was hurried through the rest of her refit with the addition of essential items like radar, splinter protection, 14 Oerlikon 20 mm and four 1.1 in light anti-aircraft guns; Maryland received a similar treatment later, the only difference being 16 20 mm's and no 1.1 in. Although tower masts were constructed for Colorado and Maryland and a majority of the old cage masts were cut down by the ships' crews in the beginning of 1942, the ships could not be spared the time needed to install the new masts. The tower masts were placed into storage and not used until early 1944.[30]

Colorado and Maryland were greatly needed in the war zone, and as such did not undergo a major refit until 1944, although minor additions and removals, mainly to the anti-aircraft weaponry, were made in-between. Throughout the war, both ships saw their anti-aircraft battery changed constantly. Beginning in 1942, they carried eight 5 in/25, four quadruple-mounted 1.1 in guns, a greatly varying number of 20 mm, and eight .50 caliber machine guns. In June 1942, Colorado had fourteen 20 mm; just five months later, this was upped to twenty-two, with thirty-six temporarily approved for a later time. By February 1943, both Colorado and Maryland had two more quad 1.1 in added (for a total of 6) and forty-eight total 20 mm; a month later she was given an additional ten .50 caliber machine guns. November 1943 saw the removal of two of the single-purpose 5 in/51, the six quad 1.1 in, and a small number of 20 mm (six in Colorado, eight in Maryland) in favor of thirty-two Bofors 40 mm—six quad and two twin.[31]

Both ships finally underwent major refits in 1944. Here the remaining cage masts were taken off in favor of the tower masts, the two twin 40 mm replaced by quads, a quadruple 20 mm added, and a new radar fitted. Although more extensive refits were proposed by Admiral Ernest J. King, including the addition of eight twin 5 in/38, more advanced fire control systems, and a second protective deck plating, the Bureau of Ships, after demonstrating what would have to be removed as compensation for the weight added for King's ideas, counter-proposed that a smaller reconstruction, like the ones given to the New Mexico class, would be more desirable. However, no action was taken until Maryland was struck by a kamikaze aircraft. While undergoing repair, eight twin 5 in/38 were added, but nothing else; her conning tower was removed and replaced by a 50 lb (23 kg) special-treated steel structure to balance the additional weight of the 5 in guns.[32]

The ship was towed out in November 1924 to be used as a gunnery target. On the first day of testing, the ship was hit by two 400-pound (180 kg) torpedoes and three 1 short ton (0.91 t) near-miss bombs with minor damage and a list of three degrees. On that day, the ship had 400 pounds of TNT detonated on board, but she remained afloat. Two days later, the ship was hit by fourteen 14-inch (360 mm) shells dropped from 4,000 feet (1,200 m), but only one penetrated. The ship was finally sunk by the battleships New York and Texas with fourteen 14 in shells. After the test, it was decided that the existing deck armor on battleships was inadequate, and that future battleships should be fitted with triple bottoms.[38]

USS West Virginia (BB-48) was the second ship of the United States Navy named in honor of the 35th state. Her keel was laid down on 12 April 1920 by the Newport News Shipbuilding and Drydock Company of Newport News, Virginia. She was launched on 17 November 1921 and commissioned on 1 December 1923, CaptainThomas J. Senn in command. Despite a grounding incident early in her career West Virginia received high acclaim for gunnery and armor protection, and was involved in exercises to test the defenses of the Hawaiian Islands in the 1930s. On the morning of 7 December 1941, West Virginia sustained heavy damage, but thanks in large part to counter flooding orders the battleship sank at her berth on an even keel, which is similar to that of California. Resurrected from the mud on 17 May 1942, West Virginia received enough patchwork to sail for Washington State; she entered Puget Sound Naval Shipyard in 1942 for repairs and modernization.[39]

In July 1944 she emerged from her repairs and overhaul, and set out to rejoin the Pacific Fleet for combat operations. She joined the fleet on the eve of the Philippines Campaign. There she participated in the Battle of Surigao Strait, the last battleship vs battleship duel of World War II, where her new Mk. 8 fire-control radar allowed her to hit the Yamashiro with her first salvo – in the dark – at 22,800 yards (20,800 m). In February 1945 West Virginia participated in the Battle of Iwo Jima, initially by preinvasion bombardment, and later by callfire support for the ground forces on the island. Her last combat operations were during the Battle of Okinawa; after the surrender of Japan, she was called upon to participate in Operation Magic Carpet. Decommissioned in 1947, she was sold for scrapping in 1959.[39]